Seems to be a regression, not sure when it was introduced exactly. This diff repositions the `ChatThreadListItemMenu` `.menuSidebar` `div` to be absolutely positioned so that it doesn't interfere with the `ChatThreadListSidebar`. Before, the `ChatThreadListSidebar` was being covered by the `ChatThreadListItemMenu` and it probably went unnoticed since it wasn't tested with a sidebar message that was long enough to trigger the ellipsis overflow.
Before:
{F76328}
After:
{F76329}